This invention relates to catheters and methods for dilating blood vessels to open occlusions and, more particularly, to coherent light transmitting dilation catheters and related methods.
Numerous catheter devices have been proposed for use in blood vessels for opening occlusions. The occluding material, commonly referred to as plaque, is often a soft jelly-like substance. When the plaque is a soft jelly-like substance, balloon percutaneous translumenal coronary angioplasty (PTCA) is frequently effective in reducing the occlusion. With PTCA, a catheter having expandable walls is inserted into the femoral artery of a patient, passes through the femoral artery into a coronary artery and penetrates the soft plaque. With the catheter in place, its walls are expanded to dilate and disperse the plaque over the interior surface of the blood vessel to open the occlusion. The catheter is then deflated and removed from the blood vessel.
Sometimes the plaque is hard and calcified rather than soft and jelly-like. If the plaque is calcified, a catheter might not be able to penetrate the plaque. In such a situation, PTCA cannot be used to open the occlusion.
Various proposals have been made for combining fiber optic bundles with a catheter for use within a blood vessel. These prior devices direct coherent light, eg., laser light, to calcified plaque within blood vessels to ablate the occlusions. One concern accompanying the use of laser energy to remove occlusions within blood vessels is perforating the walls of the blood vessels with the laser energy. Prior patents pertaining to catheters utilizing coherent energy include: U.S. Pat. No. 4,207,874 to Choy; U.S. Pat. No. 4,418,688 to Loeb; and U.S. Pat. No. 4,445,892 to Hussein et al.
The patent to Choy discloses a catheter having expandable walls for retaining the catheter within a lumen while a laser is disintegrating an occlusion. The patent to Hussein discloses a dual balloon catheter device with two spaced and expandable balloons for providing an isolated operating region between the two balloons within a blood vessel. In that device, the balloons are positioned on either side of an occlusion and the occlusion is obliterated by laser energy. The plague is then removed from the isolated region by way of a suction tube.
Other patents pertaining to catheters include: U.S. Pat. No. 3,837,347 to Tower; U.S. Pat. No. 4,261,339 to Hanson et al; U.S. Pat. No. 4,346,698 to Hanson et al; U.S. Pat. No. 4,349,029 to Mott; U.S. Pat. No. 4,404,971 to LeVeen et al; U.S. Pat. No. 4,423,725 to Baran et al; and U.S. Pat. No. 4,335,723 to Patel.
It is an object of the present invention to provide an apparatus for boring a passageway through an occlusion within a blood vessel so that a catheter may pass through the passageway.
It is a further object of the present invention to provide means which allows a balloon catheter to be placed within a passageway for dilating an occlusion.